/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkLabelImageToLabelMapFilter_hxx
#define itkLabelImageToLabelMapFilter_hxx

#include "itkNumericTraits.h"
#include "itkTotalProgressReporter.h"
#include "itkImageLinearConstIteratorWithIndex.h"

namespace itk
{
template <typename TInputImage, typename TOutputImage>
LabelImageToLabelMapFilter<TInputImage, TOutputImage>::LabelImageToLabelMapFilter()
  : m_BackgroundValue(NumericTraits<OutputImagePixelType>::NonpositiveMin())
{
  this->DynamicMultiThreadingOff();
}

template <typename TInputImage, typename TOutputImage>
void
LabelImageToLabelMapFilter<TInputImage, TOutputImage>::GenerateInputRequestedRegion()
{
  // call the superclass' implementation of this method
  Superclass::GenerateInputRequestedRegion();

  // We need all the input.
  const InputImagePointer input = const_cast<InputImageType *>(this->GetInput());
  if (!input)
  {
    return;
  }
  input->SetRequestedRegion(input->GetLargestPossibleRegion());
}

template <typename TInputImage, typename TOutputImage>
void
LabelImageToLabelMapFilter<TInputImage, TOutputImage>::EnlargeOutputRequestedRegion(DataObject *)
{
  this->GetOutput()->SetRequestedRegion(this->GetOutput()->GetLargestPossibleRegion());
}

template <typename TInputImage, typename TOutputImage>
void
LabelImageToLabelMapFilter<TInputImage, TOutputImage>::BeforeThreadedGenerateData()
{
  // init the temp images - one per thread
  m_TemporaryImages.resize(this->GetNumberOfWorkUnits());

  for (ThreadIdType i = 0; i < this->GetNumberOfWorkUnits(); ++i)
  {
    if (i == 0)
    {
      // the first one is the output image
      m_TemporaryImages[0] = this->GetOutput();
    }
    else
    {
      // the other must be created
      m_TemporaryImages[i] = OutputImageType::New();
    }

    // set the minimum data needed to create the objects properly
    m_TemporaryImages[i]->SetBackgroundValue(m_BackgroundValue);
  }
}

template <typename TInputImage, typename TOutputImage>
void
LabelImageToLabelMapFilter<TInputImage, TOutputImage>::ThreadedGenerateData(
  const OutputImageRegionType & regionForThread,
  ThreadIdType                  threadId)
{
  TotalProgressReporter progress(this, this->GetInput()->GetRequestedRegion().GetNumberOfPixels());

  using InputLineIteratorType = ImageLinearConstIteratorWithIndex<InputImageType>;
  InputLineIteratorType it(this->GetInput(), regionForThread);
  it.SetDirection(0);

  for (it.GoToBegin(); !it.IsAtEnd(); it.NextLine())
  {
    it.GoToBeginOfLine();

    while (!it.IsAtEndOfLine())
    {
      /** todo: use .Value() here? */
      const InputImagePixelType & value = it.Get();

      if (value != static_cast<InputImagePixelType>(m_BackgroundValue))
      {
        // We've hit the start of a run
        const IndexType idx = it.GetIndex();
        LengthType      length = 1;
        ++it;
        while (!it.IsAtEndOfLine() && it.Get() == value)
        {
          ++length;
          ++it;
        }
        // create the run length object to go in the vector
        m_TemporaryImages[threadId]->SetLine(idx, length, value);
      }
      else
      {
        // go the next pixel
        ++it;
      }
    }
    progress.Completed(regionForThread.GetSize(0));
  }
}

template <typename TInputImage, typename TOutputImage>
void
LabelImageToLabelMapFilter<TInputImage, TOutputImage>::AfterThreadedGenerateData()
{
  OutputImageType * output = this->GetOutput();

  // merge the lines from the temporary images in the output image
  // don't use the first image - that's the output image
  for (ThreadIdType i = 1; i < this->GetNumberOfWorkUnits(); ++i)
  {
    for (typename OutputImageType::Iterator it(m_TemporaryImages[i]); !it.IsAtEnd(); ++it)
    {
      LabelObjectType * labelObject = it.GetLabelObject();
      if (output->HasLabel(labelObject->GetLabel()))
      {
        // merge the lines in the output's object
        LabelObjectType *                           lo = output->GetLabelObject(labelObject->GetLabel());
        typename LabelObjectType::ConstLineIterator lit(labelObject);
        while (!lit.IsAtEnd())
        {
          lo->AddLine(lit.GetLine());
          ++lit;
        }
      }
      else
      {
        // simply take the object
        output->AddLabelObject(labelObject);
      }
    }
  }

  // release the data in the temp images
  m_TemporaryImages.clear();
}

template <typename TInputImage, typename TOutputImage>
void
LabelImageToLabelMapFilter<TInputImage, TOutputImage>::PrintSelf(std::ostream & os, Indent indent) const
{
  Superclass::PrintSelf(os, indent);

  os << indent
     << "BackgroundValue: " << static_cast<typename NumericTraits<OutputImagePixelType>::PrintType>(m_BackgroundValue)
     << std::endl;
}
} // end namespace itk
#endif
